Acid-catalyzed aldol-Meerwein–Ponndorf–Verley-etherification reactions—access to defined configured quaternary stereogenic centers

A novel asymmetric aldol-reduction–etherification process of aliphatic enolizable aldehydes is described. The intermediately formed aldol adducts—β-hydroxyaldehydes—were reduced and transformed into the corresponding 1,3-diol ethers by external secondary alcohols at the same time. Thus, with the help of chiral secondary alcohols an access to optically active 1,3-diol ether is given. Furthermore, asymmetric cross-aldol-Meerwein–Ponndorf reactions of enolizable aldehydes can also be realized under these reaction conditions.